Study: Exposure to herbicide may increase risk of rare disorder

A common herbicide used in the United States may be linked to an increased risk of a congenital abnormality of the nasal cavity known as choanal atresia, say researchers at Baylor College of Medicine and other Texas institutions.

The study by Dr. Philip Lupo, assistant professor of pediatrics—hematology/oncology at BCM and Texas Children’s Cancer Center, is scheduled for publication in The Journal of Pediatrics.

Affects ability to breathe

Choanal atresia is a disorder where the back of the nasal passage is blocked by tissue formed during fetal development. It is a rare condition but can be serious because it affects a baby’s ability to breathe. It is typically treated through surgery.

Very few risk factors for choanal atresia have been identified, however chemicals that disrupt the maternal endocrine system may be associated with risk, according to Lupo. The study focused on atrazine, which is the most commonly used herbicide in the United States—especially in corn crops—and is believed to be an endocrine disrupter.

"Endocrine disrupters aren’t fully understood, but it is believed they interfere with or mimic certain hormones, thereby blocking their proper function and potentially leading to adverse outcomes," Lupo said.

Discovering origin of birth defect

The study found that mothers who lived in Texas counties with the highest levels of estimated atrazine application were 80 percent more likely to have children with choanal atresia or stenosis compared to women who lived in the counties with the lowest levels. Choanal stenosis is a less severe form of the condition.

Data for the study was collected from the Texas Birth Defects Registry.

"Our results warrant more detailed exploration before any public health or policy-related recommendations are made," Lupo said, "but this study is a good first step in trying to understand the origin of this birth defect, including a possible role of atrazine."

The study was funded in part by the Centers for Disease Control and Prevention-funded Texas Center for Birth Defects Research and Prevention through a cooperative agreement with Texas Department of State Health Services as well as the Title V Office of Texas DSHS. Others involved in the research included A. J. Agopian, Yi Cai, Peter H. Langlois, and Mark A. Canfield.